Individual brick mouldings are usually produced by cutting an extruded clay strip or strand and this can occur with a variety of cutting approaches. For example, the clay strip can be continuously cut into brick mouldings immediately after emerging from the extrusion press. Alternately, the strip can be initially cut into portions and the portions then advanced into a specific position where they are cut into brick mouldings or reset into a further position for cutting into brick mouldings. Cutting can be performed with or without waste at the end of the strip or portion.
A number of different cutting apparatus have been proposed. One such apparatus comprises a plurality of spaced apart wires clamped in a cutting frame. The cutting frame reciprocates vertically and cuts the clay strip into brick mouldings as the strip emerges from a die. During cutting, the cutting frame moves, in the direction of, and in synchronism with, strip movement and the cutting frame is returned to its upper starting position during intervals between cuts. Cutting is performed during the upward and the downward movement of the cutting frame.
A disadvantage of such an apparatus, however, is that only thin-walled hollow strands can be cut which must be soft extruded, otherwise the clay strip tends to deform during upward cutting. It is also disadvantageous to cut in both the upward and downward direction because the wire cannot be guided back into the cut since the advancing motion of the clay strip causes the cut ends of the brick mouldings to be pushed against each other. Further, the cutter is complex because a substantial amount of controlling means are required to synchronize strip movement, cutting and cutting frame movement and thus too is disadvantageous.
In another known apparatus, brick mouldings are cut from a clay strip emerging from an extrusion press using wires clamped in a cutting frame, the clay strip being supported during cutting by plates. The plates and the cutting wires are movable relative to each other on return of the cutting frame to the starting position so that the wires move between the brick mouldings. In this apparatus, cutting occurs only during the downward movement of the cutting frame.
Disadvantages of this apparatus are substantially the same as those relating to the previously-described apparatus. Furthermore, because of the mass which has to be moved, output from the apparatus is limited and an even greater amount of control is required.
In another device, a portion cut from the clay strip is transferred to a separate conveyor and moved into a specific position where it is cut into brick mouldings. The conveyor includes blades spaced apart a predetermined distance and as a cutting frame, which holds cutting wires, is moved vertically the wires pass through and cut the clay strand and likewise through the spaces between the blades. After cutting, the wires are returned to a starting position whereupon the brick mouldings are advanced and a new clay strand portion is moved into cutting position.
A disadvantage of this apparatus is that the blades can have only a limited height so that when cutting through particularly hard clay strands, or strands having a large cross-section, substantial bending of the cutting wires occurs so that the middle portion of the bottom strip edge is not cut through. While the wire could be supported in the middle, so as to halve the bending length, this would produce marks on the cut surfaces of the brick mouldings.
A transfer plate is required to effect the transfer of the mouldings from the blade conveyor to an adjoining conveyor, owing to the diameter of the driving pulley required for the blade conveyor, and this prevents the reliable transfer of thin brick mouldings. Also, the brick mouldings are pushed over the transfer plate due to friction with the blade conveyor.
It is also known to push clay strands laterally through a wire hub. This apparatus can, however, be used only for cutting solid or cored bricks with thick walls.
In another cutting device, clay strand portions are transversely conveyed on a belt table including spaced apart narrow belts. During cutting, the wires of a cutting wire hub pass through the strand and the spaces between the belts. However, a separate belt table is required for each cutting length so that the apparatus becomes complex and expensive.
In yet a further cutting device, clay strand portions are held on a lifting table and are perpendicularly raised through a wire hub with the cut brick mouldings then being laterally pushed off the lifting table.
The disadvantage of this apparatus is the limited output because no fresh strip portions can pass to the cutting position while the cut brick mouldings are being pushed off. A further disadvantage is the additional mechanical complexity called for by the required transfer from one conveying device to another.